1. Technical Field
The present invention relates to a switching mechanism for a camera device and, more particularly, to a switching mechanism capable of switching filters by means of a simple mechanism so that little noise is produced, and no complicated control units are required.
2. Description of Related Art
For a general camera equipped with a CCD or CMOS sensing element to maintain a satisfactory image-capturing state in daytime as well as at night, it is necessary to switch filters for diurnal and nocturnal use of the camera respectively such that high image fidelity is achieved in the day, and clear pictures can be taken during nighttime. Therefore, filter-switching mechanisms, i.e., structures with a filter-switching function, are commonly provided in camera devices.
A filter-switching mechanism can be controlled by several methods, and from the perspective of control, these methods are divided into the following two categories:                A. Closed circuit control methods: Control is carried out with the assistance of feedback signals. In other words, after a motor is activated to drive a mechanism, and the driven mechanism reaches a predetermined position or condition, a feedback signal is sent to a control unit so as to adjust a driving state of the motor. With such control methods, the state of a driven device can be controlled, thus enabling stable operation. However, this kind of methods is disadvantaged by their relatively high costs and bulkiness.        B. Open circuit control methods: According to these control methods, a motor drives a mechanism in a one-way manner while an input unit takes charge of active control, and it is impossible to know the state of a device being controlled. While devices based on this kind of methods is simple, inexpensive, require no special controllers and feedback mechanisms, they will have to deal frequently with the problem that, in the absence of position-detecting devices (such as switches, sensors), if a movement relation between an enabling device (such as a motor) and a driven device is not cut off when the driven device is hindered, devices such as the motor or a transmission mechanism in the motion link (most probably the motor) may be damaged. To prevent such damage, a mechanism for making and breaking the aforesaid movement relation must exist in the control mechanism described above. Now that retaining and controlling are frequently administered by means of friction, noise is inevitably produced. Hence, the methods under this category are advantageous in being capable of accomplishing the target movement with a relatively compact and simple mechanism and a relatively low cost, but are inherently flawed, in terms of control, by failing to control the state of a controlled object and the noise problem.        
Hence, the inventor of the present invention, based on years of experience, proposes a switching mechanism for a camera device so as to solve the aforesaid problems.